Ping the premier connection on each network with higher priority.

webrtc/p2p/base/p2ptransportchannel.h

Index: webrtc/p2p/base/p2ptransportchannel.h
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index 672abb7423b95f1904428c0a8873d4e6c6262c32..637708262c7cd9b701f43693699cad98d1714c3d 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -43,8 +43,8 @@ namespace cricket {
 enum class IceRestartState { CONNECTING, CONNECTED, DISCONNECTED, MAX_VALUE };
 
 extern const int WEAK_PING_INTERVAL;
-extern const int STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL;
-extern const int STABLE_WRITABLE_CONNECTION_PING_INTERVAL;
+extern const int WEAK_OR_STABILIZING_WRITABLE_CONNECTION_PING_INTERVAL;
+extern const int STRONG_AND_STABLE_WRITABLE_CONNECTION_PING_INTERVAL;
 static const int MIN_PINGS_AT_WEAK_PING_INTERVAL = 3;
 
 // Adds the port on which the candidate originated.
@@ -261,7 +261,9 @@ class P2PTransportChannel : public TransportChannelImpl,
   void RememberRemoteCandidate(const Candidate& remote_candidate,
                                PortInterface* origin_port);
   bool IsPingable(const Connection* conn, int64_t now) const;
-  bool IsSelectedConnectionPingable(int64_t now);
+  // Whether a premier connection is pingable, where a premier connection is
+  // the top-ranked connection on each network.
+  bool IsPremierConnectionPingable(Connection* premier_conn, int64_t now);
   int CalculateActiveWritablePingInterval(const Connection* conn,
                                           int64_t now) const;
   void PingConnection(Connection* conn);
@@ -317,12 +319,15 @@ class P2PTransportChannel : public TransportChannelImpl,
   // Returns true if the new_connection is selected for transmission.
   bool MaybeSwitchSelectedConnection(Connection* new_connection,
                                      const std::string& reason);
-
+  // Gets all premier connections on all networks.
+  std::map<rtc::Network*, Connection*> GetPremierConnectionsByNetwork() const;
   void PruneConnections();
   bool IsBackupConnection(const Connection* conn) const;
 
   Connection* FindConnectionToPing(int64_t now);
   Connection* FindOldestConnectionNeedingTriggeredCheck(int64_t now);
+  // Finds the best premier connection for pinging.
+  Connection* FindBestPremierConnectionToPing(int64_t now);
   // Between |conn1| and |conn2|, this function returns the one which should
   // be pinged first.
   Connection* SelectMostPingableConnection(Connection* conn1,